高酸性气体对硫铝酸盐水泥石腐蚀作用机理  

Corrosion mechanisms of sulfoaluminate cement by highly sour gas

作　　者：张磊 武广瑷 武治强 幸雪松 蔡靖轩 程小伟[2,3] ZHANG Lei;WU Guangai;WU Zhiqiang;XING Xuesong;CAI Jingxuan;CHENG Xiaowei(CNOOC Research Institute Co.,Ltd.,Beijing 100028,China;School of New Energy and Materials,Southwest Petroleum University,Chengdu 610500,Sichuan,China;National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,Sichuan,China)

机构地区：[1]中海油研究总院有限责任公司 [2]西南石油大学新能源与材料学院 [3]西南石油大学油气藏地质及开发工程国家重点实验室

出　　处：《石油钻采工艺》2023年第4期432-440,454,共10页Oil Drilling & Production Technology

基　　金：中海油科研项目“文昌9-7油田开发钻完井基本设计”(编号:2022BD-11-2)。

摘　　要：为了研究硫铝酸盐水泥石在含有H_(2)S的高酸性环境的性能变化及腐蚀机理,采用氮吸附比表面积及孔径分析测试仪(BET和BJH方法)测试了腐蚀前后水泥石比表面积和孔隙结构变化,利用X射线衍射仪(XRD)和热分析仪(TG/DTG)分析了腐蚀前后水泥石水化产物的变化,采用扫描电子显微镜(SEM)观察对比了腐蚀前后水泥石水化产物微观形貌的变化。结果表明:SAC在60℃时强度发展较好,60℃腐蚀14 d后水泥石主要产物为AFt,90℃腐蚀14 d后主要生成物是CaSO_(4)·2H_(2)O;水泥石被H_(2)S腐蚀后会产生明显的分层现象,外层最先被腐蚀,内层会由于膨胀作用出现短期内的强度提高;H_(2)S的腐蚀机理为水泥水化产物中的C−S−H和CH分别与H_(2)S发生反应,生成具有膨胀性的AFt和CaSO_(4)·2H_(2)O,进而使水泥石产生裂纹,导致抗压强度下降。研究结果为硫铝酸盐水泥在高含硫油气井的固井应用提供了一定的实验及理论基础。This research investigated the property variation and corrosion mechanisms of sulfoaluminate cement in highly sour services.The variations of the specific area and pore structure of the cement after corrosion were measured by cryogenic nitrogen adsorption tests(the BET and BJH methods).The changes in hydration products after corrosion were tested using the X-ray diffractometer(XRD)and thermal analyser(TG/DTG).Finally,the micro-scale morphological variations of hydration products of cement after corrosion were observed using the scanning electron microscope(SEM).The results showed that SAC presents a desirable strength at 60℃.The hydration products are mainly Aft after 14-day corrosion at 60℃and CaSO_(4)·2H_(2)O after 14-day corrosion at 90℃.Notable stratification of the set cement is observed after corrosion by H_(2)S.The outer layer is first corroded,while the inner layer presents short-term strength growth due to swelling.The mechanism of H_(2)S corrosion is that C−S−H and CH in the hydration products of cement react with H_(2)S respectively and produce swelling Aft and CaSO_(4)·2H_(2)O,which results in cracking of cement and reduction in compressive strengths.The findings of this research provide the experimental and theoretical basis for applications of sulfoaluminate cement in cementing of oil and gas wells with highly sour gas.

关 键 词：高含硫气井 硫铝酸盐水泥 抗压强度 腐蚀机理 固井 

分 类 号：TE256[石油与天然气工程—油气井工程]